The present invention relates to a worktable for an apparatus for grinding recesses.
The apparatus for grinding recesses, which reference is made to in the following description, is a hand operated machine, also called notching machine, that is adapted for recessing, by grinding, in ends of tubular workpieces. This apparatus has a pair of pulleys carrying a grinding belt: one of the pulleys is a driving pulley for the grinding belt, and the other pulley is a shaping pulley co-operating with the grinding belt to shape recesses. A vice for clamping a pipe to be worked is located near the shaping pulley and is movable according to a movement towards and away from the shaping pulley, to allow a pipe, that is clamped by the vice, to be ground.
In order to achieve such a movement in prior art apparatuses for grinding recesses, the vice for clamping pipe is mounted rotatable on a worktable in such a position with respect to the shaping pulley that the axis of the shaping pulley and the axis of the pipe to be worked form a desired angle in a generally horizontal plane that is defined by the same axes. Usually, said angle can be changed between 90 and 30 degrees. The worktable, that is generally constituted by a pair of slides sliding on mutually orthogonal axes, has a feeding movement with respect to the shaping pulley that is obtained through two orthogonal movements and is controlled by generally manual feed means along such orthogonal axes, one of which is parallel to the axis of the shaping pulley.
These feed means comprise prismatic guides, that are usually made by a pair of parallel cylindrical sections co-operating with correspondent through holes that are made in the slides of the worktable, and parts in mutually orthogonal movement are each operated by wheels, worm screws or rack-and-pinion gears, or other, that are controlled through handwheels or lever-operated links.
In any case, the operation along one direction of the one slide in the worktable is independent of the operation of the other slide in the other direction, at right angles to the first direction. Therefore, it happens that an operator performs a recess in a tubolar workpiece by simply approaching the tubolar workpiece to the grinding belt, usually in a central position thereof widthwise. Of course, the grinding belt will be worn unevenly and its life will be reduced consequently.
Now, an operator careful to prolong the life of a grinding belt must act cunningly so that the grinding of a recess is performed throughout the width of the belt, while the belt runs endless on the two pulleys of the apparatus. This should require a great diligence of the operator.
The present invention aims at overcoming the above mentioned drawbacks.